Air conditioning system



Filed June 7, 1939 5 Sheets-Sheet l {inventors Alwin B. Newton.- James 5. Lo

May 14, 1940.

A. B. NEWTON ET AL AIR CONDITIONING SYSTEM Filed June 7, 1939 3 SheetsSheet 2 finventors Alwin. B. Newton. James S. 'fiocke y 4, 1940. A. NEWTON ET AL 2,200,243

AIR CONDITIONING- SYSTEM Filed June '7', 1939 5 Sheets-Sheet 5 g g Fig.8

ihweniors Alwin B. Newi nas 216 23; 2 30o Jame5S.I1oc1 .e 237 o j Patented May 14, 1940 UNITED STATES PATENT. OFFICE 2,200,243 AIR. CONDITIONINGSYSTEM Application June 7, 1939, Serial No, 277,822

\ J 18 Claims.

This invention relatesto an air conditioning system and more particularly to a system for summer air conditioning wherein dehumidiflca- 'tion of the air is a prerequisite to satisfactory conditioning of a space. a

This invention is more particularly directed to a control system for use in an air conditioning system wherein dehumidification of the air is effected by passing the air over a suitable dehumidifying means which may be in the form of a freely rotatable wheel mounted upon a horizontal axis, the air to be dehumidified passing through the upper portion of the wheel and a flow of heated air being passed through the lower portion of the wall for driving off moisture A which has been absorbed thereby.

It is therefore an object of our invention to provide a novel control system for an air conditioning system.

go More specifically, it i an object of this invention to provide an improved means for controlling the reactivation of a dehumidifying wheel of the kind described above.

It is a further object of this invention to provide a control means for an air conditioning system including cooling means and dehumidifying means of the kind described above and correlating the operation of the cooling means and a reactivating means for the dehumidifier in a man- 3 ner to secure maximum economy of operation.

Other objects and advantages will become apparent upon a study of the specification, claims, and appended drawings wherein like reference characters represent like parts in the various views and wherein Figure 1 is a schematic illustration with certain, parts shown in cross-section of one form of system embodying our invention,

Figure 2 is a modification of the system shown in Figure 1, and

Figure 3 is a still further modification of the system shown 'in Figure 1.

Referring more particularly to Figure 1, an air conditioning chamber is represented by the v reference characterlll, air being drawn through this chamber by means of a fan ll driven by a motor 12, the air being discharged by way of the outlet 13 into the space H to be conditioned. A return air inlet I5 is provided for causing air I from the space M to flow through the air'conditioning chamber ID. A suitable by-pass I6 around the air conditioning chamber I0 is provided, this by-pass being connected by'the duct l1 with the inlet of the fan II and being con-- nected to the return air inlet l5 by means of the duct 20. This by-pass may also be provided with a fresh air inlet 2| whereby fresh air may be drawn into the by-pass by means of the fan II. The relative volumes of air flowing through the air conditioning chamber 10 and through the 6 by-pass It may be controlled by suitable dampers 22 and 23.

These dampers may be suitably interconnected by means of a link 24 and may be operatively connected by means of the link 25 to the arm 26 10 of a motor 21. The motor 21 may be a proportioning motor of the type shown in Patent No. 2,028,110 issued to D. G. Taylor January 14, 1936. The motor 21 is shown to be controlled by a device 30 which responds to the humidity in the 15 space H. The device 30 comprises a suitable humidity responsive element 3| operatively connected to a slider arm 32 pivoted at 33 and biased by means of a spring 34 in a direction to tension the element 31. Upon an increase in humidity in the space H the element 3| will elongate and the free end of the arm 32 will move downwardly under the influence of the spring 34, the opposite movement taking place upon a decrease in the relative humidity in the space. 35 The arm 32 cooperates with a potentiometer resistance 36 to control the operation of the motor 21. The extremities of the resistance 36 are connected by means of conductors 38 and '39 with the outer terminals of the motor 21 and 30 the arm 32 is connected by means of conductor 40 with the center terminal of the motor 21. Upon a study of the aforementioned Taylor patent, it will be seen that the position of arm 26 of the motor 21 will vary as the humidity in 35 v The by-pass I6 is provided for removing mois- .ture from the air passing therethrough and for this purpose a wheel 42 formed of a suitable hygroscopic material is .provided. This wheel is pivoted about an axis 43 located outside of the 50 by-pass passageway 16 and an upper portion of this wheel extends into the by-pass 16 as illustrated in the drawing. The outer portion of the wheel is provided with a series of axially extending passageways 44 to permit passage of air 'the air passing through this chamber.

therethrough. The air passing through the wheel has a large amount of its moisture absorbed thereby, thus causing a decrease in humidity of It will accordingly be seen that as the space relative humidity increases, the adjustment of the dampers 22 and 23 in the manner above set out cause a greater amount of air to flow through the dehumidifying wheel 42 to cause an increase in the removal of moisture from the air being circulated through the space M.

The lower portion of the wheel 42 extends into a chamber 45 through which heated air is circulated for driving off moisture from the lower portion of the wheel 42. Walls 46 are provided for sealing off the center portion of the wheel from the surrounding atmosphere, these walls also forming a support for the wheel. The wheel is arranged to be freely rotatable, any suitable.

anti-friction bearings (not shown) being provided for supporting the wheel for this purpose. As long as heated air is blown through the lower portion of the wheel 42 thus driving the moisture therefrom and moisture is being absorbed by a portion of the wheel to one side of the axis, it will be obvious that the one side of the Wheel will be heavier than the other side thereof so that this unbalancing of the wheel will cause its rotation so as to continuously present different portions of the wheel in the bypass l6 and in the drying or reactivating cham- 'ber 45. In order to insure this rotation of the wheel, that portion thereof which is located in the chamber "5 may be offset from the vertical center portion thereof.

For causing a flow of air through the reactivating chamber 45, a fan 59 driven by a motor 5| is provided, the inlet of this fan being connected to a chamber 52 within which is mounted a heating element 53. This heating element may take any suitable form such as a suitable heat exchanger coil through which a heating medium such as steam or hot water is caused to flow or may be in the form of a gas burner or the like. A valve 55 controls the flow of heating medium to the coil 53 and this valve is suitably connected to a motor 56 which may be a proportioning motor similar to the damper motor 21. This motor is controlled by a control device 58 which responds to the temperature of the reactivating air leaving the wheel 42. For purposes of illustration this device is shown as comprising a bellows 60 connected by means of a capillary tube 6| to a bulb 62 located in the chamber 45 in the path of the air leaving the wheel 42. This tube, bulb, and bellows may be provided with a suitable fill whereby the bellows 6n expands or contracts as the temperature of the air at the bulb 62 increases or decreases. The bellows 60 controls the position of a potentiometer arm 64 cooperating with a potentiometer resistance 65, this arm, and resistance forming the control elements for the motor 56. As the temperature of the air at the bulb 62 decreases the arm 64 will move towards the right thus causing motor 56 to open the value 55 a proportionate amount and thus increasing the flow of heating medium into the coil 53 by an amount which is proportional to the decrease in temperature at the bulb 62. Likewise, upon an increase in temperature at the bulb 62 the motor 56 will move the valve 55 towards closed position. Thus the device 58 controls the heating coil 53 in a manner to maintain the temperature of the air leaving the wheel 42 in the reactivating chamber at a substantially constant value.

Due to the fact that the wheel 42 converts the latent heat of evaporation of the moisture of the air into sensible heat, thus causing an increase in the temperature of the air passing through the by-pass chamber I6, suitable means are provided to remove this sensible heat fromthe air. Such means are shown to comprise a suitable cooling coil 10 in the chamber l6 located downstream of the wheel 42 and a similar coil H may be located in the fresh air inlet 2| to precool the air being admitted to the chamber IS. A third cooling coil 12 may be located in the main air conditioning chamber Hi to reduce the temperature of the air flowing through this chamber. Any suitable cooling medium may be caused to flow through these cooling coils and the flow of cooling medium through the coils 10, II, and 12 may be controlled by valvesl4, l5, and 16, respectively. Motors 18, 19,- and 89 may be provided for controlling the position of the valves 14, I5, and 16, respectively, and these motors may be proportioning motors similar to the motor 21. These motors are controlled primarily in response to the humidity in the space I 4 since as the humidity in the space rises and more air is caused to circulate through the dehumidifying chamber l6, more latent heat of the air will be converted into sensible heat so that more sensible heat removal will be required.

The arm 26 of the damper motor 21 which operates in response to the humidity in the space has an extension 84 which cooperates with a potentiometer resistance 85, this arm 84 and resistance 85 forming the main control potentiometer for the motors l8, l9, and 8B. These motors are all connected in parallel and are arranged to simultaneously move the respective valves towards open or closed position so the circuit connections for controlling one of these motors will suffice to describe the operation of all the motors and for this purpose reference will be made to the motor 88 controlling the valve 16.

Located within the space H and responsive to the temperature therein is a thermostatic device 88 which is shown to comprise a bellows 89 controlling the position of a slider arm 90 which cooperates with the potentiometer 9|. This potentiometer is shown to comprise a resistance element 92 and a second resistance element 93, these elements being connected together by means of a conductor 94 having substantially no electrical resistance. As long as the temperature in the space 88 is within certain desired limits such'as 74 F. to 80 F., the arm 98 will be in engagement with the conductor 94. Should the temperature in the space become undesirably low such as below 74 F., the arm 98 will move into engagement. with the resistance 92 by reason of the contraction of the bellows 89 and if the temperature in the space should become excessively high as above 80 F., the expansion of the bellows 89 will cause the arm 90 to move into engagement with the resistance 93. As long as the temperature in the space is between the desired limits however, the motor 80 will be controlled entirely by the position of the arm 84 with respect to the resistance, 85, the arm 98 having no effect whatever on the motor 80 at this time. With the control arms 84 and 99 in the positions illustrated, it will beseen that the center terminal of the motor .89 is connected to the arm 84 as follows: from the center terarm 98, conductors 94 and 98 to the arm 84. The upper extremity of the resistance 85 is connected by means of conductors I88 and IM to the lower terminal of the motor and the opposite terminal of the motor is connected by means of conductors I82 'and I83 to the opposite ex tremity of the resistance 85. Accordingly, the operation of the motor 88 is at this time controlled directly in response to movement of the arm 84 with respect to the resistance 85 and this arm being connected to the motor 21 which in turn is'operated in response to the relative humidity in the space, therefore responds to the space humidity. Thus should the space humidity increase the arm 26 of motor 21 will move downwardly thus opening the dampers 23 and closing the dampers 22 a proportionate amount and at the same time the arm 84 will move upwardly over the resistance 85 thus decreasing the resistance between the center and lower terminal of the motor 88 whereby the valve I6 is opened an amount which is in proportion to the increase in the space relative humidity. Similarly, the motors I8 and I9 will operate to open the valves I4 and I5, respectively, a proportionate amount so that there is an increased flow of cooling medium to all of the cooling coils as a result of this increase in the space humidity.

, It may happen however" that even though the space humidity is excessively high so that a great deal of moisture is being removed from the air and the latent heat of vaporization thereof is converted into sensible heat, that the spacetemperature mayfall below the desired value. In such an event the arm 98 will begin to move toward the left over the resistance 92 thus placing resistance in the circuit to the arm 84 so that this arm has a lesser effect on the valve motors fora given movement thereof than it previously had. It should be noted that when the arm-98 is in its mid-position, that the resistance 92 is connected between the center and upper terminal of the motor 88 by means of conductors 96, 91, arm 98, resistance 92, and conductors I85 and I83, whereas the resistance 93 is connected between the center and lower ter- -minals of the motor by means of conductors 96,

91, arm 98, resistance 93, and conductors I86 and I8I so that when the arm 98 is in its mid-position these resistances balance one another and have no effect on the position of the various motors. However, upon movement of the arm 98 toward theleft over the resistance 92 by reason of the decrease in space temperature below the desired value, it will be noted that less of the resistance 92 is connected between the center and upper terminal of the motor whereasa portion'of this. resistance and the resistance 93 is now connected between the center and lower terminals of the motor. It will thus be seen that the arm 98 in addition to decreasing the sensitiveness of the arm 84 also tends to move the motors towards valve closing positions to decrease the flow of cooling medium through the various cooling coils. Similarly, uponan increase in the space tem-' perature above the desired value, the arm 98 moves over the resistance 93 which also desen- .sitizes the control arm 84 and this movement of the arm 98 has the effect of moving the motors towards valve opening positions. Accordingly, if the space temperature becomes excessive the flow of cooled medium through the cooling coils will be increasedre'gardless of the space humidity and therefore the space temperature is always maintained between certain predetermined values such as 74 F. and80 F., and between these values the operation of the cooling coils is controlled directly in accordance with the space relative humidity.

During periods of low space humidity there will be little or substantially no moisture removal effected by the dehumidifying wheel 42 and at such periods therefore it is unnecessary to operate the reactivating fan 58. Accordingly, the arm 84 carries a mercury switch 8 which is connected in the circuit to the motor 5|. Whenever the space relative humidity drops low enough the arm 28 moves upwardly thus opening the dampers 22 and closing the dampers 23 so that substantially all the air being delivered to the space I4 passes through the chamber I8 with the exception of the fresh air admitted by Way of the inlet 2|, and at such time the switch 8 will be tilted to its circuit breaking position. Power is supplied to the motor 5| from line wire H5 by way of switch II8, conductor H6, motor 5| back to line wire In. Accordingly, when the switch I I8 is moved to its open position in response to I a drop in the space relative humidity to a predetermined value, this circuit to the motor 5| will be interrupted so that the fan 68 will stop rotating and no air will therefore circulate through the reactivating chamber 52 and the lower portion of the Wheel 42. As soon as the space humidity increases to a point where dehumidification is required, however, the switch 8 will be tilted back to the position illustrated so that'the motor 5| will cause operation of the fan 58 and circulation of airthrough the chamber 52 past the heating element '53 and through the lower portion of the wheel 42, to drive off the moisture which has been absorbed by the wheel in the chamber l6.

' To review the operation of the system shown in Figure 1, the relative amounts of air that flow through the air conditioning chamber I8 and the by-pass chamber l6 are controlled in accordance with the space humidity so that as the humidity increases, an increased amount of air will flow through the chamber I 6 to be dehumidified by the wheel 42. At the same time an increase in flow of cooling medium through the various cooling coils will take place since it will ordinarily be necessary to do more sensible cooling as the amount of air passing through the by-pass- I6 increases since the air passing through the wheel 42 is increased in temperature by reason of the removal of moisture and the conversion of the latent heat of vaporization into sensible heat.

Under normal conditions the operation of the cooling coils will be controlled by the humidity responsive device 38-but should the temperature in the space become excessively high or excessively low or in other words, should it fluctuate beyond certain predetermined limits, the controller 88 will begin to assume control of the cooling coils in order to prevent the temperature from fluctuating beyond these values. The heating coil 53 for reactivating the wheel 42 is controlled in accordance with the temperature at the outlet of this wheel and the reactivating fan 58 is caused by the reference character I25.

chamber I6 is maintained constant and the cooling coils are controlled. primarily by space temperature instead of space relative humidity, no humidity responsive device being illustrated in this form of the invention. The operation of the ,reactivating fan iscontrolled in accordance with the space temperature and is also controlled in accordance with the operation of the main circulating fan II. I

The motor I2 for driving the fan II is shown to be controlled by a relay indicated generally This relay is shown to comprise a relay coil I26 and an armature I21 operatively connected to switch arms I28, I29, I30, and I3I. The arms I28, I29, and I30 cooperate with fixed contacts I32, I 33, and I34, respectively, the arms being moved into engagement with these contacts in response to energization of the relay coil I26. Upon deenergization of the coil I26, the arms move out of engagement with their respective contacts under influence of gravity or any suitable biasing means (not shown). Power is supplied to the relay coil I26 by means of a step-down transformer I36, this transformer including a high tension primary I31 connected to line wires I38 and I39 which are connected to a suitable source of power (not shown). The transformer also includes a low tension secondary I40. The energization and deenergization of the relay I25 is controlled by suitable manually operated push buttons MI and I42. The push button I4I cooperates with fixed contacts I43 and I44 and this push button is biased towards open position as illustrated. The push button I42 00- operates with contacts I45 and I46, this push button being biased towards closed position as illustrated. Upon movement of the push button I M into engagement with contacts I 43 and I44 the relay coil I26 is energized by means of the following circuit: from one side of the transformer secondary I40 through conductors I5I, I52, contact I44, push button I4I, contact I43.

conductor I53, relay coil I26 and conductor I54 to the other side of secondary I40. Upon energization of the coil I26, switch arm I28 moves into engagement with contact I32 and thus closes a maintaining circuit for the relay which is independent of the contacts I43 and I44 so that this push button need only momentarily be closed, this maintaining circuit being as follows: from the transformer secondary I40 through conductors I5I, I56, contact I45, push button I42, contact I46, conductor I58, contact I32, switch arm I28, conductor I59, relay coil I26, and conductor I54 to the other side of the secondary I40. It will thus be seen that the relay I2 5 will remain energized as long as the circuit through contacts I45 switch arm I29, contact I33, conductor I6I, motor I2, and conductor I62 to the line wire I39. .It will thus be seen that the operation of motor I2 is controlled by the push buttons I4! and I42, closure of the circuit through contacts I43 and I44 by the push button I4 I causing operation of the motor I2 and opening of the circuit through contacts I45 and I46 by the push button I42 stopping operation of themotor I2. I

The valves 14 and 16 controlling the flow of cooling medium through the coils 10 a d 12,1re-

spectively, are controlled primarily by he tem-- perature in the space I4. For this purpose a thermostat I10 is provided, this thermostat being shown to comprise a bellows I1I controllin the position of a slider arm I12 with respect to the potentiometer resistance I13. As the temperature in the space rises and arm I12 moves towards the right over the resistance I13, the motors 18 and cause the valves 14 and 16 to open an amount which is proportional to the increase in the space temperature and thus increasing the flow of cooling medium through the cooling coils. Connected in parallel with the resistance I13 to the motors 18 and 80 is a potentiometer resistance I15 with which cooperates a slider arm I16 controlled by a bellows I11 which communicates by means of the capillary tube I18 with the bulb I19 which may be located in the fresh air inlet 2| or may be located directly outdoors. This tube, bulb, and bellows may be provided with a suitable volatile fill and it will thus be apparent that the position of the arm I16 with respect to the resistance I15 will depend upon the outdoor temperature. The slider arm I16 has included in its circuit to the center terminals of the motors 18 and 80 a resistance I80 which may be a variable resistance and the presence of this resistance in the circuit to this slider arm renders this slider arm less effective than the slider arm I12. In other words, a move- .ment of the slider arm I12 through the short distance X may be sufficient to move the valves 14 and 16 from full open to full closed position whereas arm I16 may have to move through the full range of the resistance I15 to cause a similar movement of the valves. The efiect of movement of the arm I16 therefore is to adjust the position of the control range X of the arm I12 and the arrangement is such that upon an increase in the outdoor temperature the control range X will be shifted towards the right so that the thermostat I 12 will operate to maintain a somewhat higher space temperature as the outdoor temperature increases.- The circuit to the control arm I 12 includes a center tapped resistance I which serves to maintain the control range X of the arm I12 of the same length regardless of the position of this control range as determined by the outdoor temperature. It will thus be seen that the cooling coils 10 and 12 will be operated to maintain the temperature in the space I4 at a value which is adjusted in accordance with the outdoor temperature so that as the outdoor temperature increases the spacetemperature will be likewise increased in order to obtain maximum conditions of comfort within the building.

The motor 80 controlling the position of the valve 16 also controls the position of a mercury switch I which is included in the circuit to the motor 5I which drives the reactivating fan 50. When the space temperature becomes sufiiciently high, the switch I90 will be moved towards closed position and if the main ventilating fan I2'is in operation by reason of the energization of the relay I25, the motor 5| will be energized as follows: from the line wire I39 through conductor I92, switch I90, conductorI93,

contact I34, switch arm I30, conductor I94, motor 5|, and conductor I to the line wire I38. Ac-

cordingly, as long as relay I25 is energized and the space temperature is sufliciently high so that 7 switch I90 is in closed position, the motor 5I will be energized and the fan 50 will operate to cause a circulation of air through the heating chamber 52 and the lower portion of the 'dehumidifying wheel 42.

The motor 56 for controlling the operation of the heating coil 53 operates in this figure in response to the temperature of the air on the upstream side of the wheel 42. A bulb 200 is cated between the discharge from the fan 50 and the wheel 42 and is connected by means of the capillary tube 20I with a bellows 202 which controls the position of the slider arm 203 with respect to the potentiometer resistance 204. The arm I3I of the relay I26 cooperates with a pair of fixed contacts 201 and 208, the arm being in engagement with contact 201 when the relay is deenergized and with the contact 208 when the relay is energized. With the relay deenergized as illustrated, in which condition thereof the main circulating fan I I is not operating, the center terminal of the motor 56 is directly connected to the lower terminal thereof as follows: from the center terminal of the motor through conductor 2 I0, switch arm I 3|, contact 201, and conductors2|| and 2 I2. When the center and lower terminals are directly connected together in this manner the motor 56 runs to an extreme position wherein the valve 55 is closed to the flow of heating medium to the heating coil 53. However, upon energization of relay I25 and movement of arm I 3| into engagement with contact 206 the 2I6 to the upper terminal of the motor and the opposite end of resistance 204 is connected by means of conductors 2|8 and 2|2 to the lower terminal of.the motor. Accordingly, when the relay I25 is energized and the fan motor I2 is operating the heating coil 53 will be operated in accordance with the temperature of the air leaving the fan 50 and entering the wheel 42 in a manner to maintain this temperature at a substantially constant value.

Located at the inlet to the fan 50 are suitable volume dampers 225 operatively connected by means of a link 226 to a proportioning motor 221. This motor is operated in accordance with the temperature of the air leaving the wheel 42, a bulb 230 being located in the path of the air leaving the wheel and being connected by means of the capillary tube 23| to the bellows 232 which controls the position of the slider arm 233 with respect to the potentiometer resistance 234. Upon an increase in temperature of the air leaving the wheel 42 and flowing over the bulb 230, the motor 221 will be operated to move the dampers 225 towards closed position thus decreasing the amount of air circulated by the fan 50.

To review briefly the operation of the system shown in Figure 2, the cooling coils 10 and 12 are controlled primarily by space temperature, the control point of the thermostat I10 being adjusted in accordance with outside temperature. Means are provided for controlling the operation of the fan motor I2 and these control means also operate to prevent operation of the motor 5| driving the reactivating fan 50 and to close the valve 55 for the heating coil 53 when the motor I2 is not operating since there will obviously-be no need at this time for reactivating the wheel '42. It should be apparent of course that means similar to that for closing the valve 55 when the relay I25 is deenergized may also be provided for motor 5| is also controlled in accordance withthe space temperature and when the space temperature is suificiently low'the circuit to the motor is. open at the switch I90. A constant flow of air flows through the dehumidifying wheel 42 v and should the humidity of the air passing over this wheel increase sufllciently, this increase in humidity will be reflected by a rise in temperv activating motor 6|. The heating coil 53 is operated to maintain the temperature of the air entering the lower portion of the wheel 42 at a predetermined value as long as the relay 2 5 is energized and the volume of air passing through the wheel for reactivating purposes is controlled in accordance with the temperature of the air leaving the wheel. In this manner the heating coil 53 is operated in a manner to give maximum economy of operation since when the dampers 225 are moved towards closed position less air will be circulated by the fan 50 so that a smaller amount of heat will be required to maintain the temperature at the bulb 200 at the desired value.

Referring now to Figure 3 the motor I2 for driving the fan II is shown to be manuallycontrolled in the same manner as set forth in Figure 2. The cooling coils 10 and 12 are also shown as being controlled by the space thermostat I10 which may be compensated by the outdoor responsive controller I11 in the same manner as in Figure 2. A humidity responsive device 250 is illustrated for controlling the operation of the fan motor 5| in cooperation with the relay I26. This controller may include a humidity responsive" element 25I controlling the posiiton of a lever 252 carrying a mercury switch 253. When the humidity in the space rises sufliciently high the element 25I will elongate and the switch 253 will be moved to closed position and if the relay I25 is energized the motor 5| will also be energized as follows: from line wire 260 through switch 253, motor 26I, contact I34'of relay I25, arm I30, conductor 262, motor 5| and line wire 263. It will accordingly be seen that in this form of the invention the motor 5| is controlled directly by the relative humidity in the space and the energization of the main circulating fan motor I2.

The supply of heated air to the fan 50 is shown to be controlled by dampers 225 conlows 280' connected by means of the capillary tube 28I to the bulb 282 located within the honnet of the furnace. When the bonnet temperature drops sufliciently, ,the bellows 280 will collapse and the switch 211 will move towards closed position whereby a circuit to the oil burner 216 is established as follows: from line wire 285 through switch 211, conductor 286, the motor of oil burner 216 to line wire 281. Any other conventional oil burner controls may also be interposed in this circuit as will be understood.

The firing means for the furnace 275 will accordingly be operated in accordance with the bonnet temperature thereof and the amount of air taken from the bonnet and passed through the lower portion of the wheel 42 will be controlled in accordance with the temperature of the air passing through the lower portion of this wheel by controlling the position of the dampers 225. 0bviously, when the fan 50 is not operating the temperature of the bonnet will rise to the desired value rapidly and, since there will be a. very small heat loss therefrom at this time the firing means 216 will operate at infrequent intervals. The motor 5| operates whenever the humidity in the space is sufliciently high indicating that the wheel 42 is in need of reactivation, providing that the fan I I is in operation at this time.

Having described some preferred embodiments of our invention, numerous modifications may become apparent to those skilled in the art and it should be understood that the arrangements shown are for purposes of illustration only and that the invention is to be limited only by the scope of the appended claims.

We claim as our invention:

1. In an air conditioning system, an air conditioning chamber, means for circulating air through said chamber and through a space to be conditioned, cooling means in said chamber for removing sensible heat therefrom, a by-pass around said air conditioning chamber, hygroscopic dehumidifying means in said by-pass which converts latent heat of evaporation of the moisture of the air into sensible heat, thus increasing the temperature of the air passing through said by-pass, cooling means in said bypass for reducing the temperature of the dehumidified air, and means responsive to a condition to be controlled in said space in control of both of said cooling means.

2. In an air conditioning system, an air conditioning chamber, means for circulating air through said chamber and through a space to be conditioned, cooling means in said chamber for removing sensible heat therefrom, a lay-pass around said air conditioning chamber, hygroscopic dehumidifying means in said by-pass which converts latent heat of evaporation of the moisture of the air into sensible heat, thus increasing the temperature of the air passing through said by-pass, cooling means in said bypass for reducing the temperature of the dehumidified air, and means responsive to the humidity of the air in the space for controlling the relative volumes of air flowing through said chamber and through saidby-pass and for controlling the cooling means.

3. In an air conditioning system, an air conditioning chamber, means for circulating air through said chamber and through a space to be conditioned, cooling means in said chamber for removing sensible heat therefrom, a by-pass around said air conditioning chamber, hygroscopic dehumidifying means in said by-pass which converts latent heat of evaporation of the moisture of the air into sensible heat, thus increasing the temperature of the air passing through said by-pass, cooling means in said bypass for reducing the temperature of the dehumidified air, means responsive to the humidity of the air in the space in control of said cooling means, and temperature responsive means for decreasing the cooling effect of the cooling means when the temperature of the space drops below a predetermined value and increasing the cooling effect of the cooling means when the space temperature rises above a predetermined higher value regardless of the humidity of the space.

4. In an air conditioning system, air conditioning means, means for circulating air over said air conditioning means and 'throughja space to be conditioned, said air conditioning means including cooling means and moisture absorbing means, said moisture absorbing means comprising a member of hygroscopic material and arranged to continuously present different surfaces thereof to the flow of air, reactivating means to drive moisture from a portion of said member which is not exposed to the flow of air, said reactivating means including heating means and fan means for circulating air over said heating means and said portion of said member, and means responsive to a condition of the air in the space in control of said fan means.

5. In an air conditioning system, air conditioning means, means for circulating air over said air conditioning means and through a space to be conditioned, said air conditioning means including cooling means and moisture absorbing means, said moisture absorbing means comprising a member of hygroscopic material and arranged to continuously present different surfaces thereof to the flow of air, reactivating means to drive moisture from a portion of said member which is not exposed to the flow of air, said reactivating means including heating means and fan means for circulating air over said heating means and said portion of said member, means responsive to a condition of the air in the space in control of said fan means, and means responsive to the temperature of the air on the downstream side of said heating means in control of said heating means.

6. In an air conditioning system, air conditioning means, means for circulating air over said air conditioning means and through a space to be conditioned, said air conditioning means including cooling means and moisture absorbing means, said moisture absorbing means comprising a member of hygroscopic material and arranged to continuously present dilferent surfaces thereof to the flow of air, reactivating means to drive moisture from a portion of said member which is not exposed to the flow of air, said reactivating means including heating means and fan means for circulating air over said heating means and said portion of said member, means responsive to a condition of the air in the space in control of said fan means and said cooling means, and means responsive to the temperature of the air on the downstream side of said heating means in control of said heating means.

. '7. In an air conditioning system, air conditioning means, means for circulating air over said air conditioning means and through a space to be conditioned, said air conditioning means including cooling means and moisture absorbing means, said moisture absorbing means comprising a member of hygroscopic material and arranged to continuously present different surfaces thereof to the flow of air, reactivating means to drive moisture from a portion of said member which is not exposed to the flow of air, said reactivating means including heating means and fan means for circulating air over said heating means .and

said portion of said member,'meansforming a path of air around said moisture absorbing means, means responsive to the humidity of the air in the space controlling the relative amounts of air flowing past said moisture absorbing means I and around said moisture absorbing means and also controlling said fan means, means responsiveto the temperature of said space controlling saidcooling means, and means responsive to the temperature of the air leaving said heating means controlling said heating means.

8. In an air conditioning. system, air conditioning means, means for circulating air over said air conditimiing means and through a space to be conditioned, said air conditioning means including cooling means and moisture absorbing means, said moisture absorbing means comprising a member of hygroscopic material and arranged to continuously present different surfaces thereof to the flow of air, reactivating means to drive moisture from a portion of said member which is not exposed to the flow of air, said reactivating means including heating means and fan means for circulating air over said heating means and said portion of said member, means responsive to a condition of the air in the space in control of said cooling means and said fan means, means responsive to the temperature of the reactivating air leaving said member in control of the amount of air circulated therethrough by said fan means, and means responsive to the temperature of the air passing to said member in control of said heating means.

9. In an air conditioning system, air conditioning means, means for circulating air over said air conditioning means and through a space to be conditioned, said air conditioning means including cooling means and moisture absorbing means, said moisture absorbing means comprising a member of hygroscopic material and arranged to continuously present different surfaces thereof to the flow of air, reactivating means to drive moisture from a portion of said member which is not exposed to the flow of air, said reactivating means including heating means and fan means for circulating air over said heating means and said portion of said member, means responing a member of hygroscopic material and arranged to continuously present different surfaces thereof -to,the flow of air, reactivating 'means to drive moisture from a portion of said member which is not exposed to the flow of air, said reactivatingmeans including heating means and fan means for circulating air over said heating means and said portion of said member, means responsive to the temperature of the space in control of said cooling means, means responsive to the humidity of the space in control of said fans means, means responsive to the temperature of the reactivating air leaving said member controlling the supply of heated air to said fan means, and means responsive to the temperature of the air entering said fan means in control of said heating means. I

11, In an air conditioning system, an air conditioning chamber, means for circulating air through said chamber and through a space to be conditioned, a by-pass around said air conditioning chamber, a vertically mounted freely rotatable wheel formed of hygroscopic material having an upper portion thereof extending into said by-pass for removing moisture from the air passing through said by-pass, fan means for causing a circulation of air through a lower portion of said wheel for removing moisture therefrom, means for heating the air circulated by said fan means prior to passing through said Wheel, means responsive to a condition of the air in said space in control of said fan means, and means responsive to the temperature of the air leaving said heating means in control of said heating means.

12. In an air conditioning system, an air conditioning chamber, means for circulating air through said chamber and through a space to be conditioned, a by-pass around said air conditioning chamber, a vertically mounted freely rotatable wheel formed of hygroscopic material having an upper portion thereof extending into said by-pass for removing moisture from the air passing through said by-pass, fan means for causing a circulation of air through a lower portion of said wheel for removing moisture therefrom, means for heating the air circulated by said fan means prior to passing through said wheel, cooling means in said air conditioning chamber, cooling means in said b-y-pass downstream of said wheel, means responsive to the humidity in said space in control of said cooling means and said fan means, means responsive to the temperature of said space also in control of said cooling means to maintain the temperature thereof within predetermined limits, and means responsive to the temperature of the air downstream of said heating means in control of said heating means.

13. In an air conditioning system, an air conditioning chamber, means for circulating air through said chamber and through a space to be conditioned, a by-pass around said air conditioning chamber, a vertically mounted freely ture therefrom, means for heating the air circulated by said fan means prior to passing through said wheel, cooling means in said air conditioning chamber, cooling means in said by-pass downstream of said wheel, damper means controlling the relativevolumes of air passing through said chamber and through said by-pass, means responsive to the humidity of the airin said space in control of said damper means, cooling means and fan means, and means responsive to the temperature of the air downstream of said heating means in control of said heating means.

14. In an air conditioning system, an air conditioning chamber, means for circulating air through said chamber and through a space to be conditioned, a by-pass around said air conditioning chamber, a vertically mounted freely rotatable wheel formed of hygroscopic material having an upper portion thereofextending into said by-pass for removing moisture from the air passing through said by-pass, fan means for causing a circulation of air through a lower portion of said wheel for removing moisture therefrom, means for heating the air circulated by said fan means prior to passing through said wheel, means for controlling operation of said means for circulating air through said chamber, means responsive to a condition of the air in said space for controlling operation of said fan means, means responsive to the temperature of the air downstream of said heating means in control of said heating means, and means for interrupting operation of said fan means and said heating means in response to the stopping of the means for circulating air through said chamber.

15. In an air conditioning system, an air conditioning chamben, means for circulating air through said chamber and through a space to be conditioned, a by-pass around said air conditioning chamber, a vertically mounted freely rotatable wheel formed of hygroscopic material having an upper portion thereof extending into said by-pass for removing moisture from the air passing through said by-pass, fan means for causing a circulation of air through a lower portion of said wheel for removing moisture therefrom, means for heating the air circulated by said fan means prior to passing through said wheel, cooling means in said chamber and bypass, means responsive to the temperature of the spacein control of said cooling, means responsive to the operation of said cooling means in control of said fan means, damper means controlling the volume of air circulated by said fan means, means responsive to the temperature of the reactivating air leavingsaid wheel in control of said damper means, and means responsive to the temperature of the reactivating air passing to said wheel in control of said heating means.

16. In an air conditioning system, an air conditioning chamber, means for circulating air through said chamber and through a space to be conditioned, a by-pass around said air conditioning chamber, a vertically mounted freely rotatable wheel formed of hygroscopic material having an upper portion thereof extending into said by-pass for removing moisture from the air passing through said by-pass, fan means for causing a circulation of air through a lower portion of said wheel for removing moisture therefrom, means for heating the air circulated by said fan means prior to passing through said wheel, cooling means in said chamber and bypass, means responsive to the temperature ,of the space in control of said cooling, means responsive to the operation of said cooling means in control of said fan means, damper means controlling the volume of air circulated by said i'an means, means responsive to the temperature of the reactivating air leaving said wheel in control of said damper means, means responsive to the temperature of the reactivating air passing to said wheel in control of said heating means, and means responsive to the shutting down of the means for circulating air through said chamber for interrupting operation of said fan means and said heating means.

17. In an air conditioning system, an air conditioning chamber, means for circulating air through said chamber and through a space to be conditioned, a by-pass around said air conditioning chamber, a vertically mounted freely rotatable wheel formed of hygroscopic material having an upper portion thereof extending into said by-pass for removing moisture from the air passing through said by-pass, fan means for causing a circulation of air through a lower portion of said wheel for removing moisture therefrom, means for heating the air circulated by said fan means prior to passing through said wheel, cooling means in said chamber and said by-pass, means responsive to the temperature of said space in control of said cooling means, means responsive to the humidity of the space in control of said fan means, and means in control of said heating means to maintain the temperature of the reactivating air passing to said wheel at a substantially constant value. 7

18. In an air conditioning system, an air conditioning chamber, means for circulating air through said chamber and through a space to be conditioned, a by-pass around said air conditioning chamber, a vertically mounted freely rotatable wheel formed of hygroscopic material having an upper portion thereof extending. into said by-pass for removing moisture from the air passing through said by-pass, fan means for causing a circulation of air through a lower portion of said wheel for removing moisture therefrom, means for heating the air circulated by said fan means prior to passing through said Wheel, cooling means in said chamber and said by-pass, means responsive to the temperature of said space in control of said cooling means, means responsive to the humidity of the space in control of said fan means, means in control of said heating means to maintain the temperature of the reactivating air passing to said wheel at a substantially constant value, and means respon' sive to the temperature of the activating air leaving said wheel for controlling the volume of the air passing thereto'so as to maintain the temperature at a substantially constant value.

ALVVIN B. NEWTON. JAMES S. LQCKE. v 

